The step files are available for frequently modified parts, like anything attaching to the core are available. Anything else should be fairly simple to modify with an STL for reference.
These guys have summed up my reasons well. I think you could agree we get high quality remixes this way and people can not easily remove my trademark to sell the parts elsewhere. I believe this to be the best low hurdle solution. Over the years I have seen it all, and this has worked very well for us. The early days, first 6 months or so, Many many “improved”, “V2”, “must have”“better” remixes came out and just muddied the waters, most were just plain horrible. The pictures and “marketing” for them were louder than me, so people would build with the crappy parts and ask ME why it didn’t work well. I am not one to tell someone “tough I’m not helping because that is not mine”, time gets spent trying to help them.
If you need one or two Specific dimensions feel free to ask but I am not providing drawing and most dims are not super critical.
If you feel something should be changed and you are not capable of doing it feel free to share it and I will change the official parts if needed, the YZ plates and the gantry screw holes were a user suggestion.